The present invention relates to a turbine nozzle for a gas turbine stage and particularly relates to a second-stage turbine nozzle airfoil profile.
In recent years, advanced gas turbines have trended toward increasing firing temperatures and efforts to improve cooling of the various turbine components. In a particular gas turbine design of the assignee, a high output turbine that uses air cooling is undergoing development. It will be appreciated that the design and construction of the turbine buckets and nozzles require optimized aerodynamic efficiency, as well as aerodynamic and mechanical loading.
In accordance with an embodiment of the present invention, there is provided a unique turbine nozzle airfoil profile for a turbine stage, preferably the second stage, which may be defined by a unique loci of points to achieve the necessary efficiency in loading requirements whereby improved turbine performance is obtained. It will be appreciated that the nominal profile given by the X, Y, Z coordinates of Table I, which follows, define this unique loci of points. The coordinates given in inches in Table I are for a cold, i.e., room-temperature profile for each cross-section of the nozzle vane. Each defined cross-section is joined smoothly with adjacent cross-sections to form the complete airfoil shape. It will also be appreciated that as the nozzle heats up in use, the profile of the nozzle vane will change as a result of stress and temperature. Thus, the cold or room-temperature profile is given by the X, Y and Z coordinates for manufacturing purposes. Because a manufactured nozzle airfoil profile may be different than the nominal airfoil profile given in the following table, a distance of xc2x10.100 inches from the nominal profile in a direction normal to any surface location along the nominal profile and which includes any coating, defines the profile envelope for this design. The design is robust to this variation without impairment of the mechanical and aerodynamic functions.
It will also be appreciated that the airfoil can be scaled-up or scaled-down geometrically for introduction into other similar turbine designs. Consequently, the X, Y and Z coordinates of the nominal airfoil profile given below are a function of the same constant or number. That is, the X, Y and Z coordinate values given in the Table may be multiplied or divided by the same constant or number to provide a scaled-up or scaled-down version of the nozzle airfoil profile, while retaining the airfoil section shape.
In a preferred embodiment according to the present invention, there is provided a turbine nozzle having a nozzle vane in the shape of an airfoil in an envelope within xc2x10.100 inches in a direction normal to any airfoil surface location wherein the airfoil has an uncoated nominal profile substantially in accordance with Cartesian coordinate values of X, Y and Z set forth in inches in Table I with the X, Y and Z values commencing at a radially innermost aerodynamic section of the airfoil and then made relative to that section for the Z coordinate, the profiles at the Z distances being joined smoothly with one another to form the complete airfoil shape.
In a further preferred embodiment according to the present invention, there is provided a turbine nozzle having a nozzle vane in the shape of an airfoil having an uncoated nominal airfoil profile substantially in accordance with Cartesian coordinate values of X, Y and Z set forth in inches in Table I with the X, Y and Z values commencing at a radially innermost aerodynamic section of the airfoil and then made relative to that section for the Z coordinate values, the profiles at the Z distances being joined smoothly with one another to form the complete airfoil profile, the X, Y and Z values being scaled as a function of the same constant or number to provide a scaled-up or scaled-down nozzle airfoil.
In a further preferred embodiment according to the present invention, there is provided a turbine comprising a turbine nozzle having a plurality of vanes, each of said vanes being in the shape of an airfoil in an envelope within xc2x10.100 inches in a direction normal to any nozzle airfoil surface location wherein the airfoil has an uncoated nominal profile substantially in accordance with Cartesian coordinate values of X, Y and Z set forth in inches in Table I with the X, Y and Z values commencing at a radially innermost aerodynamic section of the airfoil and then made relative to that section for the Z coordinate, the profiles at the Z distances being joined smoothly with one another to form the complete airfoil shape.
In a further preferred embodiment according to the present invention, there is provided a turbine comprising a turbine nozzle having a plurality of vanes, each of said vanes being in the shape of an airfoil having an uncoated nominal airfoil profile substantially in accordance with Cartesian coordinate values of X, Y and Z set forth in inches in Table I with the X, Y and Z values commencing at the radially innermost aerodynamic section of the airfoil and the profiles at the Z distances being joined smoothly with one another to form the complete airfoil shape, the X, Y and Z values being scaled as a function of the same constant or number to provide a scaled-up or scaled-down nozzle airfoil.